Eosinophilic Pneumonia

Eosinophilic pneumonia is a group of rare infections that affects your lungs. A type of white blood cell builds up in your lungs and blood, causing inflammation and damage. Causes include smoking, allergic reactions and parasitic infections. EP may occur suddenly or worsen slowly. Medications can ease symptoms and prevent respiratory failure.


What is eosinophilic pneumonia?

Eosinophilic pneumonia (EP) is a group of rare infections affecting your lungs. If you have this condition, a type of white blood cell builds up in your lungs and blood, causing inflammation (swelling) and damage.

Eosinophilic pneumonia can affect anyone at any age, with a wide range of causes that include smoking, allergic reaction and parasitic roundworm disease. Left untreated, some cases of eosinophilic pneumonia may lead to severe complications like respiratory failure. EP can be:

  • Acute, when it develops suddenly and lasts a short time.
  • Chronic, when it slowly worsens over an extended period.

Eosinophilic pneumonia isn’t contagious. With prompt diagnosis and treatment, your healthcare provider can help you manage symptoms with medication. Full recovery is possible.


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What are eosinophils?

Eosinophils (pronounced "ee-oh-sin-oh-fills") are one of several types of white blood cells that support your immune system. Your bone marrow (soft tissue inside bones) normally produces a small number of eosinophils. In a healthy person, they represent about 1% to 5% of white blood cells.

Allergies, asthma, infections, certain medications or cancer can cause eosinophils to increase (eosinophilia). Eosinophils also release substances (enzymes and proteins) to destroy unhealthy cells.

When your body produces too many eosinophils, you can develop inflammation in your tissues or organs.

How is eosinophilic pneumonia different from typical pneumonia?

EP and typical pneumonia have different causes. Bacterial, fungal or viral infections cause typical cases of pneumonia.

EP occurs when your airways, lungs and the blood vessel walls of your respiratory system fill with eosinophils. Your condition may worsen if asthma develops, and mucus begins to block these narrowed airways.

What are the types of eosinophilic pneumonia?

There are three main types of eosinophilic pneumonia. They include:

  • Acute eosinophilic pneumonia: This type worsens quickly as your blood oxygen level falls. Most patients with AEP completely recover with treatment.
  • Chronic eosinophilic pneumonia: This type worsens slowly, over days or weeks. If untreated, it may persist over weeks or months and result in severe symptoms.
  • Löffler syndrome (simple pulmonary eosinophilic, or SPE): This form of eosinophilic pneumonia may cause no symptoms or only mild symptoms such as a dry cough. Löffler syndrome occurs due to a parasitic infection (roundworms). With treatment, the condition typically resolves within one month.

Who gets eosinophilic pneumonia?

Eosinophilic pneumonia affects people of all ages. For unknown reasons, the majority of cases — and more severe cases — peak during summer months.

Important differences exist based on the type of eosinophilic pneumonia:

  • Acute EP (AEP) most often occurs in men and people assigned male at birth between ages 20 and 40.
  • Chronic EP (CEP) is more common in women and people assigned female at birth between ages 30 and 50.

Most people with AEP currently smoke. But most patients with CEP don’t smoke, and more than half have allergic diseases, including asthma, eczema (atopic dermatitis) or allergic rhinitis (hay fever).

How common is it?

Eosinophilic pneumonia appears to be a rare disease. According to a 2020 study, fewer than 200 cases of AEP have been reported in medical literature.

However, researchers believe eosinophilic pneumonia is likely underdiagnosed because its symptoms resemble those of common viruses and lung conditions. Mild cases may go undetected, especially when the cause is unknown (idiopathic).

What conditions are similar to eosinophilic pneumonia?

Eosinophilic pneumonia involves symptoms resembling many common viral illnesses and respiratory conditions, making it challenging to accurately diagnose. These include:


Symptoms and Causes

What causes eosinophilic pneumonia?

Eosinophilic pneumonia has many causes, both infectious and noninfectious. But healthcare providers don't always know the exact cause.

Common noninfectious triggers include:

  • Allergic reactions.
  • Fungus (usually aspergillosis).
  • Inhaled toxins, such as chemical fumes or particulate metals (found in the air) or dust.
  • Medication, including commonly used antibiotics, nonsteroidal anti-inflammatory drugs (NSAIDs) or selective serotonin reuptake inhibitors (SSRIs).
  • Smoking, especially if you've had a change in cigarette smoking habits (starting smoking for the first time or smoking more often).
  • Underlying conditions, including cancer, autoimmune disease or inflammatory disease.

EP may also develop as a result of infection, usually involving parasites. It rarely develops in people with COVID-19.

What are the symptoms of eosinophilic pneumonia?

Signs of eosinophilic pneumonia vary, depending on the type and cause. Common symptoms include:

Acute eosinophilic pneumonia can worsen quickly, often within two weeks. Symptoms are usually more severe in people who smoke and may include:

Without prompt diagnosis and treatment, the oxygen in your blood may fall to dangerously low levels. This can lead to acute respiratory failure in a few hours, requiring emergency treatment.

Symptoms of chronic EP develop more slowly, sometimes months before a provider diagnoses eosinophilic pneumonia. People with CEP rarely develop respiratory failure or low blood oxygen levels. Common symptoms include:

Talk to your healthcare provider if you experience any of these symptoms. If you have difficulty breathing or chest pain, call 911 or go to the nearest emergency room.

Diagnosis and Tests

How is eosinophilic pneumonia diagnosed?

Healthcare providers diagnose eosinophilic pneumonia by asking you about your symptoms. To diagnose EP, your healthcare provider also:

It can take a while to diagnose eosinophilic pneumonia due to its common symptoms. Diagnosis is also difficult because there is no rule for how many eosinophils is too high. In some cases, providers only confirm an EP diagnosis when treatment succeeds in easing symptoms.

What tests help diagnose eosinophilic pneumonia?

Healthcare providers use bronchoalveolar lavage (BAL) as the most important test to diagnose EP. Your provider uses a flexible tube (bronchoscope) to collect fluid from your lungs to look for signs of disease. You may also have:

Your provider may recommend other specialized tests to confirm the diagnosis and rule out other conditions. Talk to your provider if you have any concerns or questions about testing.

Management and Treatment

Who might be on my care team for eosinophilic pneumonia?

Your healthcare team for eosinophilic pneumonia may include:

  • Physical therapists.
  • Lung specialists (pulmonologists).
  • Respiratory therapists.

Is there a cure for eosinophilic pneumonia?

In most cases, early diagnosis and treatment with medication can help you manage symptoms and sometimes fully recover. Following treatment guidelines can help you get back to the activities you enjoy.

Is it life-threatening?

Eosinophilic pneumonia generally doesn’t require emergency medical attention. Rarely, EP can lead to severe, life-threatening complications such as respiratory failure.

What is the treatment for eosinophilic pneumonia?

If you have a mild case of EP, your provider may not treat it. Sometimes, a medication you take is causing the EP, so your provider will recommend stopping that medication.

If you require treatment, healthcare providers treat the three main types of eosinophilic pneumonia using medication to manage the underlying cause and its symptoms. Corticosteroids to reduce swelling (inflammation) are the standard therapy and highly effective.

In severe cases of AEP, providers may recommend other treatments to prevent respiratory failure:

  • Supplemental oxygen.
  • Glucocorticoids (a type of corticosteroid).

People with CEP often take steroids for an extended period, usually months. Some may require longer treatment.


How can I reduce my risk of developing eosinophilic pneumonia?

Your ability to reduce your risk of developing eosinophilic pneumonia depends on what caused the condition. Allergies are the most common cause of high eosinophil levels and may be passed down in families (inherited). Medication can help prevent or control your immune system's allergic reactions.

A healthy lifestyle, which includes reducing or quitting smoking, can also help reduce your overall risk of disease. Your healthcare provider can discuss options to help you reduce your risk of developing eosinophilic pneumonia.

Outlook / Prognosis

How long does it take to recover from eosinophilic pneumonia?

Recovery from eosinophilic pneumonia depends on the type and severity. Many people with acute eosinophilic pneumonia recover quickly, sometimes within 48 hours after steroid treatment. Most people take one to two weeks to fully heal.

If you have chronic eosinophilic pneumonia, you’ll likely receive an oral steroid (prednisone) that you take for an extended period — for months or even years. You'll also receive treatment for any underlying conditions like asthma.

What’s the outlook?

Most people who receive prompt treatment for eosinophilic pneumonia have an excellent prognosis. Medication for acute EP can dramatically ease symptoms and lead to a complete recovery.

But more than 50% of people with chronic EP experience it again (relapse) and require longer steroid treatment, sometimes multiple times. Your healthcare provider will work with you throughout your life to manage chronic eosinophilic pneumonia and ease your symptoms.

You'll receive regular tests to check on your condition. Monitoring helps your provider adjust treatment, if needed, so you can avoid complications. Follow your provider's guidelines and keep medical appointments to ensure timely care.

Living With

Will eosinophilic pneumonia affect my quality of life?

The degree to which eosinophilic pneumonia impacts your life depends on the severity of your symptoms, any underlying condition and treatment success. You may experience a complete recovery and be able to return to your former activities.

Or, you may have to make lifestyle changes and stay on medication to control symptoms and prevent complications. Working closely with your healthcare provider, you can put the odds on your side, so you can stay as healthy and active as possible.

When should I seek care for eosinophilic pneumonia?

Seek care for eosinophilic pneumonia if you experience symptoms like shortness of breath, chest pain, fever or a cough that gets worse suddenly or over time. Your provider may refer you to a lung specialist called a pulmonologist.

A note from Cleveland Clinic

A diagnosis of eosinophilic pneumonia, a group of rare lung infections, may leave you with many questions about your health. But most people recover well with corticosteroids. Your healthcare provider can help ease your symptoms and prevent complications. They’ll work with you to develop the right treatment plan so you can get back to feeling your best. Remember to always talk to your provider if you notice any change in your health, like a cough, fever or chest pain. They’ll get to the bottom of your symptoms so you can get the treatment you need.

Medically Reviewed

Last reviewed by a Cleveland Clinic medical professional on 08/05/2022.

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